In a gas turbine engine, air is pressurized in a compressor, mixed with fuel in a combustor, and ignited for generating hot combustion gases which flow downstream through one or more turbine stages which extract energy there from. A high pressure turbine (HPT) first receives the combustion gases from the combustor and extracts energy there from for powering the compressor. A low pressure turbine (LPT) follows the HPT for extracting additional energy for providing output energy typically used for powering a fan disposed upstream of the compressor in a typical aircraft gas turbine engine application.
Turbine engines are known in the art and provide for the operation of electrical energy or production of mechanical work for transfer to associated apparatuses. Steam turbines employ the energy of a flowing fluid stream for conversion into mechanical energy. In operation of turbines it is important that the working fluid flow steadily through the turbine and that the transfer of heat through the turbine housing is negligible. The power developed for unit mass flow of fluid corresponds to the measurable difference of components in a fluid property called specific stagnation enthalpy. This fluid property comprises essentially of two parts. Enthalpy is a thermal dynamic property which in steam is a function of pressure and temperature. The second part is the kinetic energy due to motion of the fluid through the turbine. Thus, it can be appreciated that the maintenance of a fluid flow through the turbine is of importance.
Steam turbines are still in various states of evolution. In modern use the density of the steam at turbine entry, especially in multistage turbines, can be significantly greater than that at the exit. To provide responsive blades to such difference and to keep the blade heights of the turbine within practical bounds, it is desirable to divide the fluid flow. Thus, the turbine has been divided into multistage compartments including a high pressure compartment which transmits some of the steam back to the boiler for reheating, an intermediate pressure compartment and, if desired, a low pressure compartment. All compartments have turbine blades therein attached to the turbine shaft. Thus, it is of importance to have an effective blade response to this expanding steam as well as efficient fluid movement from one pressure compartment of the turbine to the other.
Accordingly, Applicant has invented a more efficient turbine by ventilating and regulating the turbine to increase the momentum of the turbine, as well as the control over the pressure to allow more efficient conversion into horse power for an electric generator.